1. Field of the Invention
The present invention relates to a storage medium having a step count calculation program stored therein, a step count calculation apparatus, and a step count calculation system. More particularly, the present invention relates to a storage medium having stored therein a step count calculation program for calculating the number of steps made by a user; a step count calculation apparatus; and a step count calculation system.
2. Description of the Background Art
Conventionally, a pedometer is attached to a body of a user and measures the number of steps in accordance with vibration received from the user. As one example of such a pedometer, Japanese Laid-Open Patent Publication No. 2004-141669 (hereafter, referred to as patent document 1) discloses a body motion detection apparatus which includes acceleration sensors. The body motion detection apparatus disclosed in the above-mentioned patent document 1 includes a plurality of acceleration sensors whose acceleration directions to be detected vary respectively. And the body motion detection apparatus determines a posture of the apparatus by using signals obtained from the respective acceleration sensors and based on the posture, detects body motions (the number of steps) of a user. For example, in the body motion detection apparatus, a waveform of acceleration is analyzed and when the acceleration is reduced from a lower threshold after the acceleration has exceeded an upper threshold, it is determined that the user has made one step.
However, it may occur that the body motion detection apparatus disclosed in the above-mentioned patent document 1 cannot accurately measure the number of steps depending on a manner in which the user carries the body motion detection apparatus. Specifically, when the user walks with the body motion detection apparatus attached to the user's clothing or with the body motion detection apparatus put into a bag, the body motion detection apparatus can detect the number of steps by detecting an acceleration generated by up and down vibration of a body, which is caused when the user walks. On the other hand, when the user walks with the body motion detection apparatus held in his or her hand, because an acceleration generated by back and forth vibration, which is caused when the user swings his or her arms, the body motion detection apparatus cannot accurately measure the number of steps. In other words, because the number of the user's steps, which corresponds to one cycle of a waveform of the acceleration generated by the body's up and down vibration, is different from the number of the user's steps, which corresponds to one cycle of a waveform of the acceleration generated by the up and down vibration which is caused by swinging his or her arms, the body motion detection apparatus cannot accurately measure the number of steps. Since the user does not always carries the body motion detection apparatus so as to generate the acceleration caused by the body's up and down vibration, it is considered that the number of steps could be erroneously detected. In addition, since when the user tries to accurately detect the number of steps, the user is subject to limitations in a manner of carrying the body motion detection apparatus, usability of the body motion detection apparatus is worsened.